The present invention relates to rotational control devices, and more particularly to a touchpad jogger that provides an interface between an operator and a touchpad surface for providing control of video tape machines in a video editing suite.
In the video editing field an operator controls the movement of video tape past play/record heads either at a tape recorder machine or remotely from an editing console. This process of controllably moving the video tape is generally referred to as "jogging". At an editing console the operator in the past has had a knob coupled to a continuous potentiometer. As the knob is rotated the change in resistance in an electrical circuit of which the potentiometer is a part is converted into a variable movement control signal for the tape recorder machine. The direction of movement is determined by the increase or decrease of resistance, and the speed of movement is determined as a function of the rate of change of the resistance, i.e., the speed at which the potentiometer is rotated.
The mechanical potentiometer system was replaced with an electronic touchpad system without any moving parts. Now an operator moves a finger or stylus in a circle over the surface of the touchpad and the movement of the video tape is controlled according to the direction and speed of the circular contact, as in the mechanical situation. Alternatively linear contact by the operator across the touchpad surface, as disclosed in co-pending U.S. patent application Ser. No. 30,778 filed Mar. 25, 1987 by Rayner et al. entitled "Touch Pad Machine Control", may produce the same result. The contact point with the touchpad is converted into a series of (x,y) positions that are sampled and input to a microprocessor system for conversion into the movement control signals.
However some operators who were used to the mechanical potentiometer systems have found it difficult to convert to the touchpad system. Therefore what is desired is a means to emulate the movement and feed of the mechanical potentiometer system in the electronic touchpad system.